CN112166330B

CN112166330B - Battery management apparatus, battery management method, and battery pack

Info

Publication number: CN112166330B
Application number: CN202080002980.2A
Authority: CN
Inventors: 林宝美
Original assignee: LG Energy Solution Ltd
Current assignee: LG Energy Solution Ltd
Priority date: 2019-01-23
Filing date: 2020-01-10
Publication date: 2023-07-04
Anticipated expiration: 2040-01-10
Also published as: JP2021524138A; KR20200091750A; JP7014374B2; EP3828567A1; KR102465294B1; US20210249885A1; EP3828567B1; EP3828567A4; US11824394B2; CN112166330A; WO2020153637A1

Abstract

Provided are a battery management apparatus, a battery management method, and a battery pack. The battery management device generates a first data set including a first current value, a first voltage value, and a first temperature value indicative of a current, a voltage, and a temperature of the battery. The battery management device generates a second data set from the first data set using an error generator. The battery management device determines a first candidate value, a second candidate value, and a third candidate value for a state of charge (SOC) according to the first current value, the first data set, and the second data set, respectively. The control unit updates the correction value if the second difference between the first candidate value and the third candidate value is smaller than the first difference between the first candidate value and the second candidate value.

Description

Battery management apparatus, battery management method, and battery pack

Technical Field

The present disclosure relates to battery state of charge (SOC) estimation.

The present application claims priority from korean patent application No.10-2019-0008921 filed in korea on 1 month 23 of 2019, the disclosure of which is incorporated herein by reference.

Background

Recently, demand for portable electronic products such as notebook computers, video cameras and mobile phones has been drastically increased, and with the widespread development of electric vehicles, energy storage batteries, robots and satellites, many studies are being conducted on batteries that can be repeatedly recharged.

Currently, commercial batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, and the like, and among them, lithium batteries have received increasing attention compared to nickel-based batteries for the advantage that they can be recharged at any time when convenient, have a very low self-discharge rate, and have a higher energy density.

One of the important parameters required to control the charge/discharge of the battery is state of charge (SOC). The SOC is a parameter indicating the relative ratio of the remaining capacity to the maximum capacity of the electric energy stored in the battery when the battery is fully charged, and may be expressed as 0 to 1 or 0% to 100%. For example, when the maximum capacity of the battery is 1000Ah (amp-hours) and the remaining capacity of the battery is 750Ah, the SOC of the battery is 0.75 (or 75%).

Amperometric and equivalent circuit models are commonly used to estimate the SOC of the battery. Based on the amperage count, the SOC of the battery is estimated based on an accumulated current value corresponding to the current flowing through the battery accumulated over time. However, there may be a difference (dissimilarity) between the SOC estimated by amperometric counting and the actual SOC due to measurement errors of the current sensor and/or external noise. An equivalent circuit model was designed to simulate the electrochemical properties of the cell. However, the battery has a nonlinear characteristic according to the operation state, and it is difficult to design an equivalent circuit model for perfectly simulating the nonlinear characteristic of the battery.

To overcome the above-described drawbacks of each of the amperometric and equivalent circuit models, battery SOC estimation using an extended kalman filter has been proposed. The extended kalman filter, which uses both amperometric and equivalent circuit models in combination, achieves a more accurate estimation of SOC than when amperometric or equivalent circuit models are used alone.

In order to estimate the SOC of the battery using the extended kalman filter, it is necessary to determine the time constant of a resistor-capacitor (RC) pair included in the equivalent circuit model and set two process noises associated with at least one state variable (e.g., SOC, overpotential).

However, since the time constant depends only on at least one of the SOC and the temperature of the battery and a fixed value is assigned to each process noise, it is difficult to appropriately adjust the reliability of each of the amperage and equivalent circuit models for the operating state of the battery and the environment in which the battery is used.

Disclosure of Invention

Technical problem

The present disclosure is designed to solve the above-described problems, and therefore, the present disclosure aims to provide a battery management apparatus, a battery management method, and a battery pack, in which a plurality of candidate values for a state of charge (SOC) of a battery are determined in each cycle, and the SOC of the battery is determined based on a relationship between the plurality of candidate values.

The present disclosure is further directed to providing a battery management apparatus, a battery management method, and a battery pack, in which reliability of each of an amperage count and an equivalent circuit model in an extended kalman filter is adjusted based on a relationship between a plurality of candidate values.

These and other objects and advantages of the present disclosure will be understood by the following description, and will become apparent from, the embodiments of the present disclosure. In addition, it will be readily understood that the objects and advantages of the present disclosure may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Technical solution

A battery management device according to an aspect of the present disclosure, comprising: a sensing unit configured to detect a current, a voltage, and a temperature of the battery; and a control unit. The control unit is configured to generate a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first temperature value indicative of the detected temperature. The control unit is configured to generate a second data set from the first data set using the error generator, the second data set comprising a second current value, a second voltage value, and a second temperature value. The control unit is configured to determine a first time constant of an equivalent circuit model of the extended kalman filter based on the first temperature value and a state of charge (SOC) in a previous cycle. The control unit is configured to determine a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous cycle. The control unit is configured to determine a first candidate value of SOC for the battery based on the first current value using the amperage count. The control unit is configured to determine a second candidate value for the SOC based on the first data set, the first time constant, and the correction value using the extended kalman filter. The control unit is configured to determine a third candidate value for the SOC based on the second data set, the second time constant, and the correction value using the extended kalman filter. The control unit is configured to determine a first difference between the first candidate value and the second candidate value. The control unit is configured to determine a second difference between the first candidate value and the third candidate value. The control unit is configured to update the correction value when the second difference is smaller than the first difference. The updated correction value is greater than a predetermined initial value.

Two values included in each of at least one of a first pair of the first current value and the second current value, a second pair of the first voltage value and the second voltage value, and a third pair of the first temperature value and the second temperature value are different from each other.

The difference between the updated correction value and the initial value may be proportional to the first difference value.

The difference between the updated correction value and the initial value may be proportional to the difference between the first difference value and the second difference value.

The control unit may be configured to update the correction value using the following equation:

D ₁ can represent a first difference, D ₂ Can represent a second difference, M ₁ Can represent a first weight, M ₂ Represents a second weight, and E _correct The updated correction value may be represented.

The control unit may be configured to: when the second difference is equal to or greater than the first difference, the correction value is updated to be equal to the initial value.

The control unit may be configured to: when the first difference is greater than the threshold, the first candidate value is determined as SOC.

The control unit may be configured to determine the second candidate value as the SOC when the first difference value is equal to or smaller than the threshold value.

The control unit may be configured to selectively output a switching signal for controlling a switch installed on a current path of the battery. When the second difference is smaller than the first difference, the control unit is configured to adjust the duty cycle of the switching signal to be lower than the reference duty cycle.

A battery pack according to another aspect of the present disclosure includes a battery management device.

A battery management method according to still another aspect of the present disclosure includes: detecting the current, voltage and temperature of the battery; generating a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first temperature value indicative of the detected temperature, generating a second data set from the first data set using an error generator, the second data set comprising a second current value, a second voltage value, and a second temperature value, determining a first time constant of an equivalent circuit model of the extended Kalman filter based on the first temperature value and the SOC in the previous period, determining a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous period, determining a first candidate value of the SOC for the battery based on the first current value using amperometric counting, using the extended Kalman filter

The filter determines a second candidate value for the SOC based on the first data set, the first time constant, and the correction value, determines a third candidate value for the SOC based on the second data set, the second time constant, and the correction value using an extended kalman filter, determines a first difference between the first candidate value and the second candidate value, determines a second difference between the first candidate value and the third candidate value, and updates the correction value when the second difference is less than the first difference. The updated correction value is greater than a predetermined initial value.

The difference between the updated correction value and the initial value may be proportional to the first difference value or proportional to the difference between the first difference value and the second difference value.

The battery management method may further include: determining the first candidate value as SOC when the first difference value is greater than the threshold value; and determining the second candidate value as the SOC when the first difference value is equal to or less than the threshold value.

Effects of the invention

According to at least one embodiment of the present disclosure, the state of charge (SOC) of the battery can be more accurately determined based on the relationship between the plurality of candidate values of the SOC for the battery determined in each cycle.

Further, according to at least one of the embodiments of the present disclosure, the reliability of each of the ampere count and the equivalent circuit model in the extended kalman filter can be adjusted based on the relationship between the plurality of candidate values.

The effects of the present disclosure are not limited to the effects mentioned above, and these and other effects will be clearly understood by those skilled in the art from the appended claims.

Drawings

Fig. 1 is an example diagram of a configuration of a battery pack according to the present disclosure.

Fig. 2 is an exemplary diagram of a circuit configuration of an equivalent circuit model of a battery.

Fig. 3 is an exemplary graph of an Open Circuit Voltage (OCV) versus state of charge (SOC) curve of a battery.

Fig. 4 and 5 are exemplary flowcharts of a battery management method according to a first embodiment of the present disclosure.

Fig. 6 and 7 are exemplary flowcharts of a battery management method according to a second embodiment of the present disclosure.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation.

Thus, the embodiments described herein and the illustrations shown in the drawings are only the most preferred embodiments of the disclosure and are intended to not fully describe the technical aspects of the disclosure, so it should be understood that various other equivalents and modifications have been made thereto at the time of filing the application.

Ordinal terms such as "first," "second," and the like are included to distinguish one element from another among the various elements, but are not intended to limit the elements by such terms.

Unless the context clearly indicates otherwise, it will be understood that the term "comprising" as used in this specification designates the presence of such elements, but does not preclude the presence or addition of one or more other elements. In addition, the term < control unit > as used herein refers to a processing unit having at least one function or operation, and this may be implemented by hardware or software or a combination of hardware and software.

Furthermore, throughout the specification, it will be further understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present.

Fig. 1 is an exemplary diagram of a configuration of a battery pack according to an embodiment of the present disclosure, fig. 2 is an exemplary diagram of a circuit configuration of an equivalent circuit model of a battery, and fig. 3 is an exemplary diagram of an Open Circuit Voltage (OCV) -state of charge (SOC) curve of the battery.

Referring to fig. 1, a battery pack 10 is configured to supply electric power required for an electric device such as an electric vehicle 1, and the battery pack 10 includes a battery 20, a switch 30, and a battery management device 100.

The battery 20 includes at least one battery cell. Each cell may be, for example, a lithium ion cell. Of course, the type of battery cell is not limited to lithium ion cells, and may include, but is not limited to, any type that can be repeatedly recharged. Each of the battery cells included in the battery 20 is electrically connected to other battery cells in series or in parallel.

The switch 30 is installed on a current path for charging and discharging the battery 20. The control terminal of the switch 30 is provided to be electrically connected to the control unit 120. The switch 30 is controlled to be turned on and off according to a duty ratio of the switching signal SS output by the control unit 120 in response to the switching signal SS being applied to the control terminal. The switch 30 may be turned on when the switching signal SS is at a high level, and the switch 30 may be turned off when the switching signal SS is at a low level.

The battery management device 100 is provided to be electrically connected to the battery 20 to periodically determine the SOC of the battery 20. The battery management device 100 includes a sensing unit 110, a control unit 120, a storage unit 130, and a communication unit 140.

The sensing unit 110 is configured to detect the voltage, current, and temperature of the battery 20. The sensing unit 110 includes a current sensor 111, a voltage sensor 112, and a temperature sensor 113.

The current sensor 111 is provided to be electrically connected to a charge/discharge path of the battery 20. The current sensor 111 is configured to detect a current flowing through the battery 20, and output a signal SI indicating the detected current to the control unit 120.

The voltage sensor 112 is provided to be electrically connected to the positive and negative terminals of the battery 20. The voltage sensor 112 is configured to detect a voltage across the positive and negative terminals of the battery 20 and output a signal SV indicative of the detected voltage to the control unit 120.

The temperature sensor 113 is configured to detect a temperature of an area within a predetermined distance from the battery 20, and output a signal ST indicating the detected temperature to the control unit 120.

The control unit 120 is operatively coupled to the sensing unit 110, the storage unit 130, the communication unit 140, and the switch 30. The control unit 120 may be implemented in hardware using at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), a microprocessor, and an electrical unit for performing other functions.

The control unit 120 is configured to periodically receive the signal SI, the signal SV, and the signal ST output by the sensing unit 110. The control unit 120 is configured to determine a first current value, a first voltage value, and a first temperature value from the signal SI, the signal SV, and the signal ST, respectively, using an analog-to-digital converter (ADC) included in the control unit 120, and store a first data set including the first current value, the first voltage value, and the first temperature value in the storage unit 130.

The storage unit 130 is operatively coupled to the control unit 120. The storage unit 130 may store programs and data necessary to perform steps described below. The storage unit 130 may include at least one type of storage medium such as a flash memory type, a hard disk type, a Solid State Disk (SSD) type, a Silicon Disk Drive (SDD) type, a multimedia card micro type, a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read Only Memory (ROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), and a Programmable Read Only Memory (PROM).

The communication unit 140 may be coupled to communicate with an external device 2 such as an Electronic Control Unit (ECU) of the electric vehicle 1. The communication unit 140 may receive a command message from the external device 2 and provide the received command message to the control unit 120. The command message may be a message requesting activation of a specific function of the battery management apparatus 100 (e.g., SOC estimation, control of on/off of the switch 30). The communication unit 140 may transmit a notification message from the control unit 120 to the external device 2. The notification message may be a message for notifying the external device 2 of the result of the function (e.g., estimated SOC) performed by the control unit 120. For example, the communication unit 140 may communicate with the external device 2 via a wired network such as a Local Area Network (LAN), a Controller Area Network (CAN), and a daisy chain, and/or a short range wireless network such as bluetooth, zigbee, and WiFi.

The control unit 120 is configured to determine a state of health (SOH) or a maximum capacity of the battery 20. The maximum capacity indicates the maximum charge amount that can be currently stored in the battery 20, and may be referred to as a "full charge capacity". That is, the maximum capacity is equal to the cumulative value of the current flowing during the discharge of the battery 20 having the SOC of 1 (=100%) until the SOC is 0 (=0%). In an example, the control unit 120 may calculate the internal resistance of the battery 20 and determine the SOH or maximum capacity of the battery 20 based on the difference between the calculated internal resistance and the reference resistance. In another example, the control unit 120 may be based on The SOC at each different point in time when the battery 20 is charged and discharged and the accumulated current value in the period of time between the two points in time are determined using the following equation 1 to determine the SOH or maximum capacity of the battery 20. Assume that the earlier of the two time points is t ₁ And the later point in time is t ₂ 。

< equation 1>

In equation 1, Q _ref Representing reference capacity, SOC ₁ Indicated at time point t ₁ Estimated SOC, SOC ₂ Indicated at time point t ₂ Estimated SOC, ΔSOC represents SOC ₁ And SOC (System on chip) ₂ Differences between i _t The indication is indicated at time point t ₁ And time point t ₂ The current value of the current detected at the time point t in between, Δc represents the current detected from the time point t ₁ By time point t ₂ Cumulative current value, Q, in a period of time of (2) _est Indicated at time point t ₂ Estimation of maximum capacity at, and SOH _new Indicated at time point t ₂ Estimation of SOH at. Q (Q) _ref Is a preset value indicating the maximum capacity when SOH of the battery 20 is 1, and may be pre-stored in the storage unit 130.

Regarding equation 1, when Δsoc is too small, Q _est May be quite different from the actual value. Accordingly, the control unit 120 may be configured to determine the SOH or maximum capacity of the battery 20 using equation 1 only when Δsoc is equal to or greater than a predetermined value (e.g., 0.5).

Hereinafter, the operation performed by the control unit 120 for estimating the SOC of the battery 20 will be described in more detail.

The control unit 120 determines a first candidate value based on the first current value using amperage counting. The first candidate value indicates an estimation of the SOC of the battery 20 in the current period. Equation 2 below may be used to determine the first candidate value.

< equation 2>

The following is a description of the symbols used in equation 2. Δt represents the time length of each cycle. k is a time index which increases by 1 each time the time Δt elapses, and indicates the number of cycles from the point in time when the predetermined event occurs to the current point in time. The event may be, for example, a start event of charge and discharge of the battery 20 whose voltage is stabilized. The voltage-stabilized battery 20 may be a battery 20 in an idle condition in which current does not flow through the battery 20 and the voltage of the battery 20 is uniformly maintained. In this case, the SOC is determined from an OCV-SOC curve defining the correspondence between the OCV and the SOC of the battery 20 using the OCV of the battery 20 at the time point when the event occurs as an index _e [0]. The OCV-SOC curve is stored in the memory unit 130.

In equation 2, i [ k+1 ]]Represents the current detected in the present period, and SOC _e [k]Representing the SOC determined by the amperometric or extended kalman filter in the previous cycle. SOC [ k+1 ]]Is a first candidate value and indicates the SOC determined using equation 2. In equation 2, i [ k+1 ]]Can use i [ k ]]Instead of.

The control unit 120 further uses an extended kalman filter to determine the second candidate value and the third candidate value. The second candidate value indicates an estimation of the SOC of the battery 20 in the current period. Before describing the second candidate value and the third candidate value, the extended kalman filter will be described.

The extended kalman filter is an algorithm for periodically updating the SOC of the battery 20 by additionally using the equivalent circuit model 200 of the battery 20 together with the amperage represented by equation 2.

Referring to FIG. 2, an equivalent circuit model 200 includes an OCV source 210, an ohmic resistor R ₁ And a resistor-capacitor (RC) pair 220.

The OCV source 210 simulates an OCV, which is the voltage between the positive and negative poles of the long-term electrochemically stable battery 20. The OCV output by OCV source 210 is a nonlinear function of the SOC of battery 20. That is, ocv=f ₁ (SOC)，SOC＝f ₂ (OCV), and f ₁ And f ₂ Are inverse functions of each other. For example, refer to fig. 3,3.3V =f ₁ (0.5) and 0.7=f ₂ (3.47V)。

The OCV output by OCV source 210 may be preset through the SOC and temperature by experiment.

Ohmic resistor R ₁ IR drop V from cell 20 ₁ And (5) associating. IR drop refers to the instantaneous change in voltage across the battery 20 when the battery 20 switches from an empty state to a charge/discharge state or vice versa. In an example, the voltage of the battery 20 measured at a point in time when the battery 20 starts to charge under an empty condition is higher than the OCV. In another example, the voltage of the battery 20 measured at a point in time when the battery 20 begins to discharge under no-load conditions is below the OCV. Ohmic resistor R ₁ The resistance value of (2) may also be preset experimentally by SOC and temperature.

RC pair 220 outputs an overpotential (also referred to as "polarization voltage") V induced by an electric double layer or the like of battery 20 ₂ And comprises resistors R connected in parallel ₂ And capacitor C ₂ . Overpotential V ₂ May be referred to as a "polarization voltage". The time constant of RC pair 220 is resistor R ₂ Resistance value of (C) and capacitor C ₂ And can be preset experimentally by SOC and temperature.

V _ecm Is the output voltage of the equivalent circuit model 200 and is equal to the OCV from the OCV source 210, across the ohmic resistor R ₁ Is defined by the IR drop V of (2) ₁ Overpotential V across RC pair 220 ₂ And (3) summing.

As the time constant of the RC pair 220 is smaller, the current sensitivity of the equivalent circuit model 200 to the current flowing through the battery 20 is higher. Conversely, as the time constant of the RC pair 220 is greater, the current sensitivity of the equivalent circuit model 200 to the current flowing through the battery 20 is lower. Under the same conditions, V as the current sensitivity of the equivalent circuit model 200 is higher _ecm The change is faster. Conversely, as the current sensitivity of the equivalent circuit model 200 is lower, V _ecm The change is more gradual.

In the equivalent circuit model 200, the overpotential in the current period may be defined as the following equation 3.

< equation 3>

In equation 3, R ₂ [k+1]Representing the resistor R in the current period ₂ Resistance value of τk+1]Representing the time constant, V, of RC pair 220 in the current cycle ₂ [k]Represents the overpotential in the previous period, and V ₂ [k+1]Representing the overpotential in the current cycle. In equation 3, i [ k ] can be used]Instead of i [ k+1 ]]. Overpotential V at the time point when the event occurs ₂ [0]May be 0V (volts).

Equation 4 below is a first state equation associated with the time update process of the extended kalman filter and is derived from a combination of equations 2 and 3.

< equation 4>

In equation 4 and equations 5 to 8 below, the superscript symbol indicates the value estimated by the time update. In addition, superscript symbol ^- Indicating the value before correction by the measurement update described below.

Equation 5 below is a second state equation associated with the time update process of the extended kalman filter.

< equation 5>

In equation 5, P _k Representing the error covariance matrix corrected in the previous cycle, Q _k Represents the process noise covariance matrix in the previous cycle, T represents the transpose operator, and P ^- _k+1 Representing the error covariance matrix in the current period. When k=0, P ₀ May be equal to [1 0;0 1]。W _1k Is the first process noise set in the previous cycle and is associated with the reliability of the amperage count. Namely, W1 _k Is a positive number indicating inaccuracy of the integrated current value calculated using amperage. W2 _k Is the second process noise set in the previous cycle and is associated with the reliability of the equivalent circuit model 200. Namely, W2 _k Is a positive number indicating inaccuracy of the parameters associated with the equivalent circuit model 200. Accordingly, the control unit 120 may increase the first process noise as the inaccuracy of the amperage count increases. As the inaccuracy of the equivalent circuit model 200 increases, the control unit 120 may increase the second process noise.

When the time update process using equations 4 and 5 is completed, the control unit 120 performs a measurement update process.

Equation 6 below is a first observation equation associated with the measurement update process of the extended kalman filter.

< equation 6>

In equation 6, K _k+1 Representing the kalman gain in the current period. In addition, R is a measurement noise covariance matrix, and has a preset component. H _k+1 Is a system matrix and is used to reflect the change in OCV of the battery 20 according to an OCV-SOC curve when estimating the SOC of the battery 20. n is a preset positive integer (e.g., 1).

Equation 7 below is a second observation equation associated with the measurement update process of the extended kalman filter.

< equation 7>

In equation 7, z _k+1 Represents the voltage of the battery 20 measured in the current cycle, and V _ecm [k+1]Representing the output voltage of the equivalent circuit model 200 in the current period. f (f) ₁ (SOC[k+1]) Representing OCV in the current period (see description of fig. 2). V (V) ₁ [k+1]Representing the trans-ohmic resistor R in the current period ₁ And may be equal to i [ k+1 ]]And i [ k ]]One of which is with R ₁ [k+1]Is a product of (a) and (b). R is R ₁ [k+1]Is the ohmic resistor R in the current period ₁ Is a resistance value of (a). The control unit 120 may determine R based on the first temperature value and the SOC determined in the previous cycle ₁ [k+1]. For this purpose, the definition of SOC, temperature value and ohmic resistor R is recorded in the memory cell 130 ₁ A first look-up table of correspondence between resistance values. The control unit 120 may obtain a resistance value mapped to a specific temperature value (e.g., a first temperature value) and a specific SOC from the first lookup table using the specific temperature value and the specific SOC as indexes. SOC [ k+1 ] obtained from equation 4 ]And V ₂ [k+1]Is corrected by equation 7.

The following equation 8 is a third observation equation associated with the measurement update process of the extended kalman filter.

< equation 8>

In equation 8, E represents an identity matrix. P obtained from equation 5 ^- _k+1 Corrected to P by equation 8 _k+1 。

The control unit 120 periodically updates the SOC of the battery 20 in the current period by performing each calculation step of equations 4 to 8 at least once every time the time index k increases by 1.

Hereinafter, the operation of determining the second candidate value and the third candidate value will be described with reference to the above description of the extended kalman filter.

The control unit 120 determines a second candidate value based on the first data set. As previously described, the first data set includes a first current value, a first voltage value, and a first temperature value. The control unit 120 determines R of equation 4 based on the first temperature value and the SOC determined in the previous cycle ₂ [k+1]And τ [ k+1 ]]。

For this purpose, the memory unit 130 may record a second lookup table defining the SOC, the temperature value and the resistor R ₂ Corresponding relation between resistance values of (a). The control unit 120 may obtain a resistance value mapped to the first temperature value and the SOC determined in the previous period from the second lookup table using the first temperature value and the SOC determined in the previous period as an index as R of equation 4 ₂ [k+1]. In addition, the storage unit 130 may record a third lookup table defining a correspondence relationship among the SOC, the temperature value, and the time constant. The control unit 120 may obtain a time constant mapped to the first temperature value and the SOC determined in the previous period as the first time constant from the third lookup table using the first temperature value and the SOC determined in the previous period as indexes. The control unit 120 may set a value obtained by adding the first time constant to the correction value determined in the previous period to τk+1 of equation 4]. When k=0, a predetermined initial value (e.g., 0) may be used as the correction value. The determination of the correction value will be described below.

The control unit 120 will be of equation 4i[k+1](or i [ k ]]) Set equal to the first current value and set z of equation 7 _k+1 Is set equal to the first voltage value. Therefore, the control unit 120 may correct the SOC [ k+1 ] corrected by equation 7]And determining as a second candidate value.

The control unit 120 converts the first data set into a second data set and determines a third candidate value based on the second data set. In detail, the control unit 120 may generate the second data set from the first data set using an error generator. The control unit 120 operates the error generator to forcibly vary at least one of the first current value, the first voltage value, and the first temperature value included in the first data set in consideration of the detection accuracy of the sensing unit 110 or external noise. The second data set includes a second current value, a second voltage value, and a second temperature value. That is, the error generator may be a predetermined function that is coded to selectively make at least one of a change from a first current value to a second current value, a change from a first voltage value to a second voltage value, and a change from a first temperature value to a second temperature value. For example, the second current value= (first current value×x ₁ )+X ₂ Second voltage value= (first voltage value X ₃ )+X ₄ And the second temperature value= (first temperature value X ₅ )+X ₆ 。X ₁ To X ₆ May be constant preset to be the same or different from each other.

Two values included in each of at least one of the pair of first and second current values, the pair of first and second voltage values, and the pair of first and second temperature values are different from each other. In an example, the first and second current values may be equal to each other, while the first and second voltage values may be different from each other, and the first and second temperature values may also be different from each other. In another example, the first and second current values may be different from each other, the first and second voltage values may be different from each other, and the first and second temperature values may also be different from each other.

When generating the second data set, the control unit 120 may determine equation 4 based on the second temperature value and the SOC determined in the previous periodR ₂ [k+1]And τ [ k+1 ]]。

In detail, the control unit 120 may obtain the resistance value mapped to the second temperature value and the SOC determined in the previous period from the second lookup table as R of equation 4 ₂ [k+1]. The control unit 120 may obtain a second time constant mapped to a second temperature value and the SOC determined in the previous cycle from a third lookup table. The control unit 120 may set a value obtained by adding the second time constant to the correction value to τk+1 of equation 4 ]。

The control unit 120 will i [ k+1 ] of equation 4](or i [ k ]]) Is set equal to the second current value instead of the first current value. In addition, the control unit 120 will determine z of equation 7 _k+1 Is set equal to the second voltage value instead of the first voltage value. Therefore, the control unit 120 may correct the SOC [ k+1 ] corrected by equation 7]And determining as a third candidate value.

When the determination of the first, second, and third candidate values for the SOC of the battery 20 is completed in the current period, the control unit 120 is configured to select any one of the first and second candidate values, and determine the selected candidate value as the SOC in the current period through a process described below.

The control unit 120 determines a first difference value, which is an absolute value of a difference between the first candidate value and the second candidate value. In an example, when the first candidate value is 0.51 and the second candidate value is 0.52, the first difference value is 0.01. In another example, when the first candidate value is 0.77 and the second candidate value is 0.75, the first difference value is 0.02.

The control unit 120 determines a second difference value, which is an absolute value of the difference between the first candidate value and the third candidate value. In an example, when the first candidate value is 0.61 and the third candidate value is 0.64, the second difference value is 0.03. In another example, when the first candidate value is 0.38 and the second candidate value is 0.36, the second difference value is 0.02.

The control unit 120 may compare the first difference value with a predetermined threshold. The threshold value is stored in the storage unit 130, and may be, for example, 0.03.

When the first difference is greater than the threshold, the control unit 120 may determine the first candidate value as the SOC of the battery 20.

When the first difference value is equal to or less than the threshold value, the control unit 120 determines the second candidate value as the SOC of the battery 20 instead of the first candidate value.

The control unit 120 may compare the first difference with the second difference. When the second difference is equal to or greater than the first difference, the control unit 120 may set the ratio of the second process noise to the first process noise to be equal to a predetermined reference ratio (e.g., 0.1). For example, the first process noise may be set equal to a predetermined first reference value (e.g., 0.1), and the second process noise may be set equal to a predetermined second reference value (e.g., 0.01). That is, the reference ratio may be equal to a value obtained by dividing the second reference value by the first reference value.

When the second difference is equal to or greater than the first difference, the control unit 120 may set the correction value equal to the initial value. The control unit 120 may store the correction value set equal to the initial value in the storage unit 130.

Meanwhile, referring to equation 2 regarding amperage counting, the first candidate value depends only on the current among the current, voltage, and temperature of the battery 20. On the other hand, referring to equations 3 to 8 regarding the extended kalman filter, the second candidate value may depend on the current of the battery 20 and the voltage and temperature of the battery 20. When this is considered, it can be seen that as the inaccuracy of the equivalent circuit model 200 is higher, there is a higher likelihood that the second difference will be less than the first difference.

Accordingly, when the second difference is smaller than the first difference, the control unit 120 may increase the ratio of the second process noise to the first process noise to be higher than the reference ratio. In an example, the first process noise may be set to a value less than a first reference value (e.g., 0.07) and the second process noise may be set to be equal to a second reference value. In another example, the first process noise may be set equal to a first reference value and the second process noise may be set to a value greater than a second reference value (e.g., 0.02). In yet another example, the first process noise may be set to a value less than the first reference value and the second process noise may be set to a value greater than the second reference value.

When the second difference is smaller than the first difference, the control unit 120 may determine a ratio of the second process noise to the first process noise in proportion to the first difference. In an example, when the first difference is 0.01, the control unit 120 may determine the ratio of the second process noise to the first process noise to be 0.11, when the first difference is 0.013, the control unit 120 may determine the ratio of the second process noise to the first process noise to be 0.112, and when the first difference is 0.008, the control unit 120 may determine the ratio of the second process noise to the first process noise to be 0.103.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may determine the ratio of the second process noise to the first process noise in proportion to the absolute value of the difference between the first difference and the second difference.

The first process noise and the second process noise set as described above may be respectively assigned to W1 of equation 5 in the process of estimating SOC of the next cycle _k And W2 _k . Therefore, when the extended kalman filter is performed in the next cycle, the reliability (i.e., influence) of the equivalent circuit model 200 is temporarily reduced, and the reliability of the ampere count is temporarily increased.

When the second difference is smaller than the first difference, the control unit 120 may update the correction value to a value greater than the initial value. The control unit 120 may store the updated correction value in the storage unit 130.

When the second difference is smaller than the first difference, the control unit 120 may determine the updated correction value such that the difference between the updated correction value and the initial value is proportional to the first difference. For example, when the first difference is 0.01, the updated correction value may be determined to be 5 larger than the initial value, and when the first difference is 0.013, the updated correction value may be determined to be 6 larger than the initial value.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may determine the updated correction value such that a difference between the updated correction value and the initial value is proportional to a difference between the first difference and the second difference. For example, when the first difference is greater than the second difference by 0.01, the updated correction value may be determined to be greater than the initial value by 4, and when the first difference is greater than the second difference by 0.013, the updated correction value may be determined to be greater than the initial value by 4.5.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may update the correction value using the following equation 9.

< equation 9>

In equation 9, D ₁ Represents a first difference, D ₂ Representing a second difference, M ₁ Represents a first weight, M ₂ Represents a second weight, and E _correct Representing the updated correction value. M is M ₁ And M ₂ May be a preset positive number, and they may be the same as or different from each other.

The correction value updated as described above may be stored in the storage unit 130, and may be added to each of the first time constant and the second time constant to be obtained in the next cycle in the process of estimating the SOC for the next cycle.

In detail, in determining the second candidate value based on the first data set in the next period, a sum of the updated correction value and the first time constant in the next period may be assigned to τ [ k+1] of equation 4. In addition, in determining the third candidate value based on the second data set in the next period, a sum of the updated correction value and the second time constant in the next period may be assigned to τ [ k+1] of equation 4.

As previously described, the greater the time constant of the RC pair 220, the lower the current sensitivity of the equivalent circuit model 200. When the extended kalman filter is performed in the next cycle, τk+1 of equation 4 increases the difference between the updated correction value and the initial value, and thus, the reliability (i.e., influence) of the equivalent circuit model 200 temporarily decreases and the reliability of the ampere count temporarily increases.

The control unit 120 may selectively output the switching signal SS to control the switch 30. When the second difference is smaller than the first difference, the control unit 120 may adjust the duty ratio of the switching signal SS to be lower than a predetermined reference duty ratio (e.g., 0.2). When the duty cycle of the switching signal SS is adjusted to be lower than the reference duty cycle, the maximum amount of current that can flow through the battery 20 is reduced, thereby avoiding rapid changes in the voltage and temperature of the battery 20.

Fig. 4 and 5 are exemplary flowcharts of a battery management method according to a first embodiment of the present disclosure. The methods of fig. 4 and 5 may be performed periodically from the point in time when the event occurs. The methods of fig. 4 and 5 may end when the charge/discharge of the battery 20 stops.

Referring to fig. 1 to 5, in step S400, the control unit 120 determines the maximum capacity (or SOH) of the battery 20 (see equation 1).

In step S405, the control unit 120 detects the current, voltage, and temperature of the battery 20 using the sensing unit 110. The sensing unit 110 outputs a signal SI indicating the detected current, a signal SV indicating the detected voltage, and a signal ST indicating the detected temperature to the control unit 120.

In step S410, the control unit 120 receives the signal SI, the signal SV, and the signal ST, and generates a first data set including a first current value indicating the current of the battery 20, a first voltage value indicating the voltage of the battery 20, and a first temperature value indicating the temperature of the battery 20.

In step S412, the control unit 120 generates a second data set from the first data set using an error generator. The second data set includes a second current value, a second voltage value, and a second temperature value.

In step S420, the control unit 120 determines a first candidate value of SOC for the battery 20 based on the first current value using amperage counting (see equation 2).

In step S430, the control unit 120 determines a second candidate value of SOC for the battery 20 based on the first data set using the extended kalman filter (see equations 3 to 8).

In step S440, the control unit 120 determines a third candidate value of SOC for the battery 20 based on the second data set using the extended kalman filter (see equations 3 to 8). In contrast to fig. 4, any two or all of steps S420, S430 and S440 may be performed simultaneously. The order of steps S420, S430 and S440 may be changed as necessary.

In step S450, the control unit 120 determines a first difference between the first candidate value and the second candidate value.

In step S460, the control unit 120 determines a second difference between the first candidate value and the third candidate value. In contrast to fig. 4, steps S450 and S460 may be performed simultaneously. The order of steps S450 and S460 may be changed as necessary.

In step S500, the control unit 120 determines whether the first difference is greater than a threshold. When the value of step S500 is yes, step S510 is performed. When the value of step S500 is no, step S520 is performed.

In step S510, the control unit 120 determines the first candidate value as the SOC of the battery 20.

In step S520, the control unit 120 determines the second candidate value as the SOC of the battery 20.

In step S530, the control unit 120 determines whether the second difference is smaller than the first difference. When the value of step S530 is no, step S540 is performed. When the value of step S530 is yes, at least one of steps S550 and S560 is performed.

In step S540, the control unit 120 sets the ratio of the second process noise to the first process noise to be equal to the reference ratio. For example, the first process noise may be set equal to a first reference value and the second process noise may be set equal to a second reference value. The reference ratio is a value obtained by dividing the second reference value by the first reference value.

In step S550, the control unit 120 increases the ratio of the second process noise to the first process noise to be higher than the reference ratio.

In step S560, the control unit 120 adjusts the duty ratio of the switching signal SS output to the switch 30 to be lower than the reference duty ratio. The difference between the adjusted duty cycle and the reference duty cycle may be proportional to the difference between the first difference and the second difference.

Fig. 6 and 7 are exemplary flowcharts of a battery management method according to a second embodiment of the present disclosure. The methods shown in fig. 6 and 7 may be performed periodically from the point in time when the event occurs. The methods of fig. 6 and 7 may end when the charge/discharge of the battery 20 is stopped.

Referring to fig. 1 to 3, 6 and 7, in step S600, the control unit 120 determines the maximum capacity (or SOH) of the battery 20 (see equation 1).

In step S605, the control unit 120 detects the current, voltage, and temperature of the battery 20 using the sensing unit 110. The sensing unit 110 outputs a signal SI indicating the detected current, a signal SV indicating the detected voltage, and a signal ST indicating the detected temperature to the control unit 120.

In step S610, the control unit 120 receives the signal SI, the signal SV, and the signal ST, and generates a first data set including a first current value indicating the current of the battery 20, a first voltage value indicating the voltage of the battery 20, and a first temperature value indicating the temperature of the battery 20.

In step S612, the control unit 120 generates a second data set from the first data set using an error generator. The second data set includes a second current value, a second voltage value, and a second temperature value.

In step S614, the control unit 120 determines a first time constant of the equivalent circuit model 200 based on the first temperature value and the SOC in the previous cycle.

In step S616, the control unit 120 determines a second time constant of the equivalent circuit model 200 based on the second temperature value and the SOC in the previous cycle. As described above, each of the first time constant in step S614 and the second time constant in step S616 may be obtained from the third lookup table. In contrast to fig. 6, steps S614 and S616 may be performed simultaneously, or step S616 may precede step S614.

In step S620, the control unit 120 determines a first candidate value of SOC for the battery 20 based on the first current value using the amperage count (see equation 2).

In step S630, the control unit 120 uses the extended kalman filter for determining a second candidate value of the SOC of the battery 20 based on the first data set, the first time constant, and the correction value (see equations 3 to 8).

In step S640, the control unit 120 determines a third candidate value of the SOC for the battery 20 based on the second data set, the second time constant, and the correction value using the extended kalman filter (see equations 3 to 8). In contrast to fig. 6, any two or all of steps S620, S630, and S640 may be performed simultaneously. The order of steps S620, S630, and S640 may be changed as necessary.

In step S650, the control unit 120 determines a first difference between the first candidate value and the second candidate value.

In step S660, the control unit 120 determines a second difference between the first candidate value and the third candidate value. In contrast to fig. 6, steps S650 and S660 may be performed simultaneously, or step S660 may precede step S650.

In step S700, the control unit 120 determines whether the first difference is greater than a threshold. When the value of step S700 is yes, step S710 is performed. When the value of step S700 is no, step S720 is performed.

In step S710, the control unit 120 determines the first candidate value as the SOC of the battery 20.

In step S720, the control unit 120 determines the second candidate value as the SOC of the battery 20.

In step S730, the control unit 120 determines whether the second difference is smaller than the first difference. When the value of step S730 is no, step S740 is performed. When the value of step S730 is yes, at least one of steps S750 and S760 is performed.

In step S740, the control unit 120 sets the correction value equal to the initial value.

In step S750, the control unit 120 updates the correction value to a value greater than the initial value (see equation 9). When steps S630 and S640 are performed in the next cycle, the correction value updated in step S750 may be used to determine the second candidate value and the third candidate value.

In step S760, the control unit 120 adjusts the duty ratio of the switching signal SS output to the switch 30 to be lower than the reference duty ratio. The difference between the adjusted duty cycle and the reference duty cycle may be proportional to the difference between the first difference and the second difference.

Although the battery management methods of fig. 4 and 5 and the battery management methods of fig. 6 and 7 are described separately, when a specific step of either one of the two battery management methods is performed, a specific step of the other battery management method may be performed together. In an example, when step S740 is performed, step S540 may be performed together. In another example, when step S750 is performed, step S550 may be performed together.

The embodiments of the present disclosure described above are not only implemented by the apparatus and method, but also may be implemented by a program that performs a function corresponding to the configuration of the embodiments of the present disclosure or a recording medium having the program recorded thereon, and a person skilled in the art can easily implement such implementation from the disclosure of the previously described embodiments.

While the present disclosure has been described above with respect to a limited number of embodiments and figures, the present disclosure is not so limited, and it will be apparent to those skilled in the art that various modifications and changes can be made therein within the technical aspects of the present disclosure and the equivalent scope of the appended claims.

In addition, since many substitutions, modifications and changes may be made by those skilled in the art without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the above-described embodiments and the drawings and some or all of the embodiments may be selectively combined to allow various modifications.

Claims

1. A battery management device comprising:

a sensing unit configured to detect a current, a voltage, and a temperature of the battery; and

a control unit configured to generate a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage and a first temperature value indicative of the detected temperature,

wherein the control unit is configured to:

generating a second data set from the first data set using an error generator, the second data set comprising a second current value, a second voltage value and a second temperature value,

determining a first time constant of an equivalent circuit model of an extended kalman filter based on the first temperature value and a state of charge (SOC) in a previous period,

determining a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous cycle,

Determining a first candidate value of SOC for the battery based on the first current value using amperage,

determining a second candidate value for the SOC based on the first data set, the first time constant and a correction value using the extended kalman filter,

determining a third candidate value for the SOC based on the second data set, the second time constant and the correction value using the extended kalman filter,

determining a first difference between the first candidate value and the second candidate value,

determining a second difference between the first candidate value and the third candidate value, and

updating the correction value when the second difference is smaller than the first difference, and

wherein the updated correction value is greater than a predetermined initial value, and

wherein two values included in each of at least one of a first pair of the first current value and the second current value, a second pair of the first voltage value and the second voltage value, and a third pair of the first temperature value and the second temperature value are different from each other.

2. The battery management device of claim 1 wherein a difference between the updated correction value and the initial value is proportional to the first difference value.

3. The battery management device of claim 1 wherein a difference between the updated correction value and the initial value is proportional to a difference between the first difference value and the second difference value.

4. The battery management device of claim 1, wherein the control unit is configured to update the correction value using the following equation:

wherein D is ₁ Representing the first difference, D ₂ Representing the second difference, M ₁ Represents a first weight, M ₂ Represents a second weight, and E _correct Representing the updated correction value.

5. The battery management device of claim 1, wherein the control unit is configured to: when the second difference is equal to or greater than the first difference, the correction value is updated to be equal to the initial value.

6. The battery management device of claim 1, wherein the control unit is configured to: when the first difference is greater than a threshold, the first candidate value is determined to be the SOC.

7. The battery management device of claim 6, wherein the control unit is configured to: when the first difference is equal to or less than the threshold, the second candidate value is determined as the SOC.

8. The battery management device of claim 1, wherein the control unit is configured to:

selectively outputting a switching signal for controlling a switch installed on a current path of the battery, and

and when the second difference value is smaller than the first difference value, the duty ratio of the switching signal is adjusted to be lower than the reference duty ratio.

9. A battery pack comprising the battery management device according to any one of claims 1 to 8.

10. A battery management method comprising:

detecting the current, voltage and temperature of the battery;

generating a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first temperature value indicative of the detected temperature;

generating a second data set from the first data set using an error generator, the second data set comprising a second current value, a second voltage value, and a second temperature value;

determining a first time constant of an equivalent circuit model of an extended kalman filter based on the first temperature value and a state of charge (SOC) in a previous cycle;

determining a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous cycle;

Determining a first candidate value of SOC for the battery based on the first current value using amperage;

determining a second candidate value for the SOC based on the first data set, the first time constant, and a correction value using the extended kalman filter;

determining a third candidate value for the SOC based on the second data set, the second time constant, and the correction value using the extended kalman filter;

determining a first difference between the first candidate value and the second candidate value;

determining a second difference between the first candidate value and the third candidate value; and

11. The battery management method according to claim 10, wherein a difference between the updated correction value and the initial value is proportional to the first difference value or proportional to a difference between the first difference value and the second difference value.

12. The battery management method of claim 10, further comprising:

determining the first candidate value as the SOC when the first difference value is greater than a threshold value; and

when the first difference is equal to or less than the threshold, the second candidate value is determined as the SOC.

13. The battery management method of claim 10, further comprising updating the correction value using the following equation:

14. The battery management method according to claim 10, further comprising updating the correction value to be equal to the initial value when the second difference value is equal to or greater than the first difference value.

15. The battery management method of claim 10, further comprising: